1. Field of the Invention
The present invention relates to the production of polyisobutylene. The present invention also relates to catalysts used in organic compound conversion reactions. More particularly, the present invention the relates to plasticizer compositions having internal vinylidene molecules.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Polyisobutylene is a commercially important polymer that finds a great number of applications exploiting its thermal, stability, good flexibility at ambient temperatures, and impermeability to gases. Polyisobutylene has many properties that differentiate it from most other polymers. First, polyisobutylene has a first markedly low permeability to small molecule penetrants. Secondly, polyisobutylene has one of the weakest temperature dependencies of structural relaxation and viscosity (i.e., low fragility) and, correspondingly, strong inelastic scattering (boson peak) even at temperatures much above the glass transition. Polyisobutylene also has a very small difference between the temperature dependencies of segmental and chain relaxations, which can lead to an apparent conformance to time-temperature superpositioning, unlike the obvious breakdown seen in other polymers such as polystyrene, polyvinyl acetate, and polypropylene. Polyisobutylene also has a mechanical segmental dispersion much broader than expected for such a low fragility material. Polyisobutylene also has a very unusual spectrum of fast dynamics, that is, a “constant loss” regime where the susceptibility changes negligibly with frequency. Polyisobutylene can be viewed as a very unusual polymer with properties deviating from behavior common for many other polymers.
Polyisobutylene is an isobutylene polymer containing one double bond per polymer molecule. In high-reactive polyisobutylene, the double bond is at or near the end of the polymer chain making the product more reactive. When the double bond is located at internal positions, polyisobutylene is less reactive, creating low-reactive polyisobutylene.
The polymerization of isobutylene using a Friedel-Craft type catalyst, including boron trifluoride, is a generally known procedure. The degree of polymerization of the products obtained varies according to which a number of known polymerization techniques is used. In this latter connection, it is understood that the molecular weight of the polymer product is directly related to the degree of polymerization. It is also known that polyisobutylene can be manufactured in at least two different major grades, i.e. regular and high vinylidene. Conventionally, these two product grades have been made for different processes, but both often and commonly use a diluted isobutylene feedstock in which the isobutylene concentration can range from 40 to 60% by weight. More recently, it has been noted that at least high vinylidene polyisobutylene may be produced using concentrated feedstock having an isobutylene content of 90% by weight or more. Non-reactive hydrocarbons, such as isobutane, n-butane and/of other lower alkanes, commonly present in petroleum fractions, may also be included in the feedstock as diluents. The feedstock may also contain small qualities of other unsaturated hydrocarbons, such as 1-butene and 2-butene.
Regular grade polyisobutylene may range in molecular weight from 500 to 1,000,000 or higher, and is generally prepared in a batch process at low temperature, sometimes as low as −50° C. to −70° C. RAlCl2 or R2AlCl are often used as catalysts. The catalyst is generally not totally removed from the final polyisobutylene product due to the processing peculiarities. Molecular weight may be controlled by temperature since the molecular weight of the product varies inversely with temperature. That is to say, higher temperatures produce lower molecular weights. Reaction times are often in the order of hours. Regular polyisobutylene may be used as a viscosity modifier, particularly in lube oils, as a thickener, and as a tackifier for plastic films and adhesives. Polyisobutylene can also be functionalized to produce intermediates for the manufacture of detergents and dispersants for fuel and lube oils.
Traditional processes to make high-reactive polyisobutylene use a liquid polymerization catalyst. The catalyst is continually fed to the reactor and mixed with isobutylene monomer. The liquid catalyst is toxic, hazardous, and requires special handling systems and procedures to avoid exposure and vapor release. As the reaction mixture leaves the reactor, the catalyst must be completely neutralized and separated. The separation process involves washing the neutralized catalyst complex from the reaction mixture with copious amounts of water to remove all catalyst residues. Trace amounts are corrosive to subsequent processing steps and detrimental to product quality and stability. The neutralized catalyst cannot be recycled. This process substantially increases plant capital investment, increases operating costs, and generates approximately as much waste water as product.
FIG. 1 is an illustration of the polymerization mechanism for isobutylene. Isobutylene is made by the cationic polymerization of isobutylene, generally by using a Lewis acid catalyst. These catalysts typically include AlCl3, BS3, and complexes of BS3. The first step is the initiation step (I) and involves association of the catalyst with the isobutylene monomer so as to give the initial carbocations. The propagation step (P) is the second step where additional monomer adds to initial carbocation so as to generate a new carbocation at the end of the growing chain. Chain propagation continues until a desired number of monomer units (molecular weight) is reached. The termination step (T) occurs when carbocation reacts with the catalyst residue instead of another monomer unit, consequently generating a double bond. The termination step (T) and the propagation step (P) are competing reactions. The propagation step (P) is favored at lower reaction temperatures. The termination step (T) is favored at higher reaction temperatures. Therefore, the polymer molecular weight is inversely proportional to reaction temperature. Higher reaction temperatures produce lower molecular weight and lower reaction temperatures produce higher molecular weights.
The termination step (T) can produce two major olefin isomers, namely, alpha vinylidene (Structure 1) and beta tri-substituted olefin (Structure 2). Structure 1 is kinetically preferred since it forms more rapidly. Structure 2, and other substituted olefins, are thermodynamically preferred and more stable. Accordingly, Structure 1 can isomerize to less desirable Structure 2 and higher substituted olefins. To prevent isomerization and “lock in” the preferred Structure 1 isomer, the polymerization catalyst needs to be neutralized or isolated rapidly from the reaction mixture. There are several ways this is accomplished. In particular, one of the steps is neutralization with basic pH media and subsequent removal by conventional means, such as absorption onto active substrates or through the use of conventional separation techniques.
A great number of different types of catalyst systems have been proposed in the past for conducting organic compound conversion reactions. These systems include the use of (1) metal oxide BF3 complexes, (2) BF3 and liquid BF3 complexes as catalysts for isobutylene polymerization, (3) liquid BF3 methanol complexes as isobutylene polymerization catalysts, and (4) solid isobutylene polymerization catalysts. Prior art relevant to these prior art systems is discussed below.
Inorganic metal oxides, such as alumina, have been provided with catalytic activity in the past by contacting the same with BF3, usually in gaseous form. The contacting is usually followed by hydrolysis and calcination or some other post-treatment. These catalysts generally have limited activity, are not stable and release free BF3 into the reaction products requiring post reaction removal of these residues.
U.S. Pat. No. 2,804,411, assigned to American Oil Company, discloses treatment of a Si stabilized gelled alumina with gaseous BF3. Free BF3 is required to be added to the reaction mixture.
U.S. Pat. No. 2,976,338, assigned to Esso, describes an olefin polymerization catalyst comprising a BF3H3 PO4 complex that may be absorbed onto a solid support.
U.S. Pat. No. 3,114,785, assigned to UOP, describes an olefin isomerization catalyst made by contacting anhydrous gamma or theta alumina with gaseous BF3 at temperatures from about 100° C. to 150° C. for 10 hours or until alumina is saturated. The process of olefin isomerization using the BF3-alumina catalyst is claimed; the composition of the catalyst is not claimed.
U.S. Pat. No. 4,407,731, assigned to UOP, claims catalytic compositions of matter prepared by pre-treating a metal oxide, such as alumina, with aqueous acid and base followed by calcination. The treated gamma alumina is then treated with BF3 gas at temperatures of 308-348° C. at elevated pressure to obtain the final catalyst useful for oligomerization and alleviation reactions.
U.S. Pat. No. 4,427,791, assigned to Mobil Oil Co., discloses a method for enhancing the activity of metal oxides, such as alumina, by treating the alumina with NH4F or BF3, contacting this fluoride-containing product with an ammonium exchange solution and then calcinating the final product.
U.S. Pat. No. 4,918,255, assigned to Mobil Oil Co., describes an isoparaffin alkylation catalyst based on metal oxides and aluminosilicate zeolites treated with a Lewis acid, including BF3, in the presence of a controlled amount of water or water-producing material. Excess BF3, to that needed to saturate the metal oxide is used requiring post reaction BF3 removal.
U.S. Pat. No. 4,935,577, assigned to Mobil Oil Co., describes a catalytic distillation process using a non-zeolite metal oxide activated with BF3 gas. Excess BF3, above that needed to saturate the metal oxide, is used requiring post reaction BF3 removal BF3 and liquid BF3 complexes as catalysts for isobutylene polymerization.
The homogenous catalytic polymerization of olefins using gaseous BF3 and liquid BF3 complexes is well known. The polymers generally so produced are of the highly reactive type wherein a large percentage of the polymer contains terminal double bonds or has a high vinylidene content. All of these processes require post-reaction removal of the BF3 catalyst.
U.S. Pat. No. 4,152,499, issued to Boerzel et al., describes the synthesis of polyisobutylene having a degree of polymerization of 10-100 units using a blanket of BF3 gas as the catalyst. The polyisobutylene product was then reacted with maleic anhydride in yields of 60-90% indicating a large portion of vinylidene end groups.
U.S. Pat. No. 4,605,808, issued to Samson, describes production of a polyisobutylene having at least 70% unsaturation in the terminal position. An alcohol complex of BF3 was used as the catalyst. The complexing of the BF3 seems to give better control of the reaction and higher vinylidene content.
U.S. Pat. No. 7,411,104, assigned to Daelim Industrial Co., describes a method for producing highly reactive polyisobutylene from a raffinate-1 stream using a liquid BF3 secondary alkyl ether-tertiary alcohol complex. The process requires low reaction temperatures and the catalyst complex is not stable and must be made in situ. The catalyst must be removed from the reactor effluent by a post-reaction treatment process.
U.S. Pat. No. 5,191,044, issued to Rath et al., discloses a process for preparing polyisobutylene in which the BF3 catalyst is completely complexed with an alcohol such that there is no free BF3 in the reactor or in the reaction zones. An excess of alcohol complexing agent is required to assure that no free BF3 is present. The reaction times are on the order of 10 minutes with reaction temperatures of below 0° C.
Rath, in U.S. Pat. No. 5,408,018, describes a multistage process for preparing highly reactive polyisobutene with a content of terminal vinylidene groups of more than 80 mol % and an average molecular weight of 500-5000 Daltons by the cationic polymerization of isobutene or isobutene-containing hydrocarbon feeds in liquid phase with the aid of boron trifluoride as catalyst and at from 0° C. to −60° C. The polymerizing is in the presence of secondary alcohols with 3-20 carbon atoms and/or ethers with 2-20 carbon atoms.
Olefin polymerization, especially isobutylene polymerization, is an exothermic process. Control of reaction temperature is critical to product quality, catalyst life, degree of polymerization and obtaining the desired pre-selected properties. In the patents cited above, the reaction temperature was controlled by dilute olefin monomer concentration, complexed catalyst, multi-stage reactions and/or long reaction times and low reaction temperatures. Low reaction temperatures increase energy requirements; long-reaction times or dilute feed streams increase equipment size and equipment cost (capital expenditures).
U.S. Pat. Nos. 6,525,149, 6,562,913, 6,683,138, 6,884,858 and 6,992,152, to Baxter, et al. describe olefin polymerization processes in which the polymerization is carried out in the tube side of a heat exchanger under turbulent flow conditions. The reactor design allows for very effective and efficient removal of the heat of reaction such that relatively high feed rates and concentrated feed streams may be used. A BF3-methanol complex is used as the catalyst and because this complex is particularly stable, higher reaction temperatures may be used. The BF3-methanol catalyst complex may be preformed, formed in-situ by separate injection of the methanol completing agent, or a combination of both.
The BF3 methanol complexes are very stable allowing for higher isobutylene polymerization temperatures not possible with other BF3 oxygenate complexes, particularly higher alcohols, secondary alcohols, ethers and the like. Also, because higher reaction temperatures may be used, reaction rates are increased.
However, in all of the patents cited above, the BF3, or at least portions of the BF3, catalysts are soluble in the polymer products. Residual BF3 is detrimental to product quality and must be removed as quickly as possible. Hence, these processes must employ some kind of catalyst quench and catalyst removal steps subsequent to the reaction. The quenched BF3 streams cannot be recycled and the BF3 is lost.
Isobutylene and butylene polymerizations have also been conducted using solid catalysts, particularly Friedel-Crafts type catalysts, such as AlCl3. The advantage to these processes is that the catalyst is a solid and is not soluble in the product. Catalyst removal and product purification is much easier than in the BF3 catalyzed reactions.
U.S. Pat. No. 2,484,384, assigned, to California Research Corporation, U.S. Pat. No. 2,677,002, assigned to Standard Oil Co., U.S. Pat. No. 2,957,930, assigned to Cosden Petroleum Corporation and U.S. Pat. No. 3,119,884, assigned to Cosden Petroleum Corporation, all describe AlCl3 catalyzed butylene polymerization processes using a fluidized bed reactor system.
U.S. Pat. No. 4,306,105, assigned to Cosden Petroleum Corporation, describes a chlorinated alumina catalyst prepared by reacting pure alumina with pore chlorine. A fluidized bed reactor is utilized for butene polymerization.
Solid catalysts have also been used to produce olefin polymers with a high proportion of terminal vinylidene groups.
U.S. Pat. No. 5,710,225, assigned to Lubrizol, claims the use of phosphotungstic acid salt to polymerize C2-C3 olefins to produce polymers with molecular weights in the range of 300-20,000. The use of phosphotungstic catalyst, in a fixed bed reactor, is also described, but the flow rate is low and is generally operated as a plug flow reactor. The resulting polymer has an undesirable very high polydispersity. The fixed bed reactor as described in the example would not be economically feasible.
U.S. Pat. No. 5,770,539, assigned to Exxon Chemical Patents, Inc., discloses heterogeneous Lewis acids polymerization catalysts, such as BF3, immobilized in porous polymer substrates. The BF3 is complexed with the aromatic rings of cross-linked polystyrene copolymers.
U.S. Pat. No. 5,874,380, assigned to Exxon Chemical Patents, Inc., claims a solid state insoluble salt catalyst system for the carbocationic polymerization of olefin monomer in the presence of polar or non-polar reaction medium which comprises at least one salt of a strong acid and a carbocationically active transition metal catalyst selected from Groups IIIA, IVA, VA, and VIA of the Periodic Table of the Elements.
U.S. Pat. No. 6,384,154, assigned to BASF Aktiengesellshaft, discloses a process for preparing halogen-free, reactive polyisobutylene by cationic polymerization over an acidic, halogen-free heterogeneous catalyst comprising oxides and elements from transition or main group I, II, III, IV, V, VI, VII or VIII of the Periodic Table of the Elements. The polymerization is carried out in a fixed bed reactor.
The solid, heterogeneous butylene polymerization catalysis cited above do solve the problem of catalyst residues in the reactor effluent, thereby eliminating the need for post reaction treatment. However, conversions are low, space velocities are low and reaction temperatures are low.
BF3 activated metal oxides are not described in the prior art as polymerization catalysts for the manufacture of polybutene or polyisobutylene. In fact, U.S. Pat. No. 6,710,140 assigned to BASF Aktiengesellshaft claims the use of alumina as a solid deactivator to absorb BF3 catalyst residues from polyisobutylene reactor effluents. The resulting BF3-alumina complex is described as not catalytic.
It is an object of the present intention to provide a polyisobutylene composition and process for forming the polyisobutylene composition which avoids the use of washing water and produces no wastes.
It is another object of the present invention to provide a polyisobutylene composition and process for forming the polyisobutylene composition which is a green process.
It is still another object of the present invention to provide a polyisobutylene composition and process for forming polyisobutylene composition which avoids the need for recycling.
It is still another object of the present invention to provide a polyisobutylene composition and process for forming the polyisobutylene composition which produces high yields of high purity product.
It is a further object of the present invention to provide a polyisobutylene composition and process for forming the polyisobutylene composition which is simple and highly effective.
It is still a further object of the present invention to provide a polyisobutylene composition and process for forming the polyisobutylene composition which involves a significantly reduced capital investment, low operating costs and low catalyst costs.
If is still a further object of the present invention to provide a polyisobutylene composition and process for forming the polyisobutylene composition that provides the ability to make anhydride succinics, succinimide, mannich, and split-tail surfactants.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.